Time transformation of local activation times

Abstract

An automatic method of determining local activation time (LAT) from at least four multi-channel cardiac electrogram signals including a ventricular channel, a mapping channel and a plurality of reference channels. The method comprises (a) storing the cardiac channel signals, (b) using the ventricular and mapping channel signals and a first reference channel signal to compute LAT values at a plurality of mapping-channel locations, (c) monitoring the timing stability of the first reference channel signal, and (d) if the timing stability of the monitored signal falls below a stability standard, using the signal of a second reference channel to determine LAT values. Substantial loss of LAT values is avoided in spite of loss of timing stability.

Description

FIELD OF THE INVENTION[0001]This invention is related generally to the field of electrophysiology, and more particularly to technology for accurate measurement of parameters within body-surface ECG, intracardiac, and epicardial electrical signals such as heart rates and local activation times and the assessment of the quality of such measurements.BACKGROUND OF THE INVENTION[0002]The invention disclosed herein involves the processing of multiple channels of electrical signals which are produced by the heart. These channel signals include the ECG signals from body-surface electrodes and signals from electrodes within the body, i.e., intracardiac signals from within vessels and chambers of the heart and epicardial signals from the outer surface of the heart. Throughout this document, the term “multi-channel cardiac electrogram” (or “MCCE”) is used to refer to all of these types of channels, and when specific types are appropriate, specific nomenclature is used. This new terminology (MC...

AI Technical Summary

Benefits of technology

The present invention is an automatic method for determining local activation time (LAT) from cardiac electrogram signals. This method can quickly and reliably measure LAT without interfering with the procedures performed by electrophysiologists. The method involves storing the signals, using a ventricular channel and a mapping channel to compute LAT values at multiple locations, and monitoring the timing stability of the reference channel signal. If the signal becomes unstable, a second reference channel signal is used to determine LAT values and avoid significant loss of information. Overall, this invention provides a reliable and efficient way to measure LAT, which is important for studying cardiac electrophysiology.

Problems solved by technology

Cardiac interventional electrophysiology procedures (e.g., ablation) can be extremely time-consuming, and the reliable determination and presentation of such cardiac parameters is an important element in both the quality of the procedures and the speed with which they can be carried out.

Often the data which are presented to the electrophysiology doctor during such procedures exhibit high variability contributed not only by the performance of the heart itself but by unreliable detection of certain features of the MCCE signals.

The electrical signals within the heart muscles and which flow therefrom to other regions of the body have very low voltage amplitudes and therefore are susceptible to both external signal noise and internally-generated electrical variations (non-cardiac activity).

In addition, cardiac arrhythmias themselves may be highly variable, which can make reliable extraction of cardiac parameters from MCCE signals difficult.

Occasionally a reference electrode is bumped or becomes disconnected.

In these cases, additional data cannot be collected to extend the map (add more LAT values to the map) because the timing relationships are no longer comparable (based on the same reference channel signal).

At a few seconds of signal acquisition per location, a few seconds of catheter motion between locations, and hundreds of locations, the amount of time and effort wasted if a map must be restarted can be very significant.

Furthermore, extending the total procedure time adds more risk of complications for the patient.

Occasionally a reference electrode either makes poor contact or may shift position, in which case the constant timing relationship is disrupted (timing stability is lost) and additional locations cannot be studied in relationship to accumulated data.

As described above, the resulting incomplete activation map may be worthless, requiring a new map, extending the procedure and adding cost and risk to the patient.

Currently-available MCCE-processing algorithms are simplistic and often provide inaccurate measurements which cause the activation map and many other cardiac parameter values to be misleading.

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